Q: Migrating iPhotos to Photo from external device.

I am trying to migrate my old iPhoto album from an external time machine to my new macbook air, but keep getting following msg: "Photos was unable to repair permissions on your library." My old macbook no longer powers up.  Can I get my pics?  I have plugged my time machine into my macbook air, option clicked the "Photos" app, then selected "other library", then went into the latest back-up from my old computer into the "iPhoto" library.  That's when I get the message.  Any help?  I'm especially concerned because my old macbook won't boot up anymore and I expected all of my things to be safe on a backup.  Thanks for any insight.